Candidate Tumor-Suppressor Gene Regions Responsible for Radiation Lymphomagenesis in F1 Mice with Different p53 Status

Regions of allelic loss on chromosomes in many tumors of human and some experimental animals are generally considered to harbor tumor-suppressor genes involved in tumorigenesis. Allelotype analyses have greatly improved our under-standing of the molecular mechanism of radiation lymphomagenesis. Previously, we and others found frequent loss of heterozygosity (LOH) on chromosomes 4, 11, 12, 16 and 19 in radiation-induced lymphomas from several $F_1$, hybrid mice. To examine possible contributions of individual tumor-suppressor genes to tumorigenesis in p53 heterozygous deficiency, we investigated the genome-wide distribution and status of LOH in radiation-induced lymphomas from $F_1$ mice with different p53 status. In this study, we found frequent LOH (more than 20%) on chromosomes 4 and 12 and on chromosomes 11, 12, 16 and 19 in radiation-induced lymphomas from $(STS/A{\times}MSM/Ms)F_1$ mice and $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice, respectively. Low incidences of LOH (10-20%) were also observed on chromosomes 11 in mice with wild-type p53, and chromosomes 1, 2, 9, 17 and X in p53 heterozygous-deficient mice. The frequency of LOH on chromosomes 9 and 11 increased in the $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice. Preferential losses of the STS-derived allele on chromosome 9 and wild-type p53 allele on chromosome 11 were also found in the p53 heterozygous-deficient mice. Thus, the putative tumor-suppressor gene regions responsible for lymphomagenesis might considerably differ due to the p53 status.